1. Field of the Invention
The invention relates to a water hammering prevention device.
2. Description of the Prior Art
It has been a common practice to use an accumulator installed in the middle of the piping system of the water supply device to achieve such an object.
Such a device has a sealed container whose inside is divided into the water supply pressure side and the pressure suction side by means of a rubber bladder, diaphragm, piston,. etc., so that the pressure surge due to the water hammering action generated at the water supply pressure side can be absorbed.
However, there was a limit to the absorption of the pressure surge due to the water hammering action because the pressure absorption side of the abovementioned device is a closed space.
With the abovementioned problem in mind, the present invention intends to provide a water hammering prevention device including: an outer box having concentric flow paths for an inlet and an outlet and a drain port in the midstream section of the flow path; an inner tube member having a diaphragm on its periphery dividing the inside of the outer box into an upstream section and an area consisting of a midstream section and a downstream section of the flow path, wherein the inner tube member slidingly fits into the upper section; a relief valve is provided on the end face of the downstream side opening of the inner tube member and the relief valve is capable of moving toward or away from a valve seat located on the periphery of a valve port provided between the midstream section and the downstream section and energized by a relief valve spring toward the valve opening direction; and a check valve provided inside the inner tube member to prevent fluid from flowing backward from the downstream side, thus solving the abovementioned problem by discharging the pressurized water caused by the water hammering action to the outside via the drain port.
The invention, constituted as such, checks the upstream side with the check valve 5 and opens the relief valve 4 when the back pressure rises above the upstream pressure due to water hammering, so that the back pressure from downstream can be discharged to the outside through the drain port 9, thus eliminating noise and vibration due to water hammering completely and drastically reducing piping system problems, which used to be caused at least partially by noise and vibration due to water hammering.
In accordance with one aspect of the invention, the water hammering prevention device is installed parallel to the check valve 38 installed in the piping 39 of the water supply device 34, or directly in the piping 39, and the drain port 9 is connected via piping to the water receiving tank 35, so that it not only prevents water hammering completely but also it adds an economic effect of eliminating wasteful use of water as the water drained from the drain port 9 is returned to the water receiving tank 35.
In accordance with another aspect of the invention, a water hammering prevention device is connected to each of the terminal devices 51, 51a of the water supply device 45 and their drain ports 9 are connected to the outside, so that it is capable of preventing water hammering caused by frequent high back pressure rises due to repeated turning on and off of the water supply, particularly when the terminal devices 51, 51a are high pressure water injection guns, by discharging the high pressure fluid to the outside through the drain port 9.
By connecting the drain ports 9 via piping to the water receiving tank 47, water waste can be prevented as well.
In accordance with a further aspect of the invention, the effective diameter D1 of the diaphragm 14 and the valve seat diameter D2 of the valve seat 11 are chosen to be about equal so that the valve closing pressure of the relief valve 4 that the diaphragm 14 receives and the valve opening pressure that the relief valve 4 itself receives can be balanced and the spring loads F and f of the relief valve spring 17 and the check valve spring 28 respectively are chosen to maintain the pressure P2 of the midstream section 8b always lower than the upstream side pressure P1 by a margin of xcex94P of a constant value. It is therefore possible to provide, by setting the pressure difference xcex94P between the pressure P2 of the midstream section 8b and the upstream side pressure P1 to match the individual characteristic of a water supply device, a specific valve opening characteristic for the relief valve 4 to suit the characteristics of a particular water supply device, thus being able to provide a water hammering prevention device 1 that fits with any water supply device.
In accordance with another aspect of the invention, the inner tube member 3 is formed to have a circular cross section, while the sliding surface 12 of the inside of the outer box 2 that fits with the inner tube member 3 has grooves 13, 13a equally spaced along its circumference, so that it is possible to reduce the sliding contact area between the inner tube member 3 and the sliding surface 12 and to make the inner tube member 3 thinner and lighter without sacrificing strength, thus contributing to reducing the sliding resistance of the inner tube member 3 as much as the strength of the inner tube member allows. Consequently, it is possible to improve the water supply performance because of the reduction of the pressure loss of the pressurized fluid during the water supply period and to use a smaller water supply pump for the water supply device.
In accordance with yet another aspect of the invention, it is possible to reduce the friction resistance of the inner tube member 3 against the outer box 2 because of a coating on the outer circumference of the inner tube member 3 of Teflon and to reduce the pressure loss in the same way as in the case above.
In accordance with still another aspect of the invention, the check valve 5 has a flat surface 30 formed on its face 29 confronting the check valve port 18, the surface having a diameter smaller than the check valve port 18, and a conical apex 31 formed in the middle of the flat surface 30. Furthermore, multiple tilting grooves 33, 33a are provided having a groove width decreasing gradually toward the center of the back of the check valve 5 from the outer periphery, which is further outside of a seating area 32 corresponding to the check valve seat 19. These tilting grooves 33, 33a are equally spaced in the circumferential direction on the check valve 5. As a result, water flows smoothly from upstream to downstream along the shape of the check valve 5 without causing any swirls on the back of the check valve 5, thus minimizing the pressure loss due to the check valve inserted in the flow path 8. It provides similar effects as mentioned above and its practical benefit is significant.